A karshen karni na 11, jarumin Burgundian Henry ya zama kidaya na Portugal kuma ya kare 'yancin kai ta hanyar hade gundumar Portugal da gundumar Coimbra.Yaƙin basasa da ya barke tsakanin León da Castile ya taimaki ƙoƙarinsa kuma ya raba hankalin abokan gabansa.Ɗan Henry Afonso Henriques ya ɗauki iko da gundumar bayan mutuwarsa.Birnin Braga, cibiyar Katolika ba bisa ka'ida ba na yankin Iberian Peninsula, ta fuskanci sabuwar gasa daga wasu yankuna.Mahukuntan garuruwan Coimbra da Porto sun yi fafatawa da limaman Braga kuma sun bukaci yankin da aka sake ginawa ya samu 'yancin kai.Yaƙin São Mamede ya faru ne a ranar 24 ga Yuni 1128 kusa da Guimarães kuma ana ɗaukarsa a matsayin taron koli na kafuwar Masarautar Portugal da yaƙin da ya tabbatar da 'Yancin Portugal.Dakarun Portugal karkashin jagorancin Afonso Henriques sun fatattaki sojojin da mahaifiyarsa Teresa ta Portugal da masoyinta Fernão Peres de Trava ke jagoranta.Bayan São Mamede, sarki na gaba ya sanya kansa "Prince of Portugal".Za a kira shi "Sarkin Portugal" daga 1139 kuma masarautun makwabta sun gane shi a cikin 1143.